I would be really very uncomfortable to run Furmark, it not good idea to run it for 1 hour because it can cause damage to videocard's VRM after 1 hour. I searched internet about this and people are told not to dare run furmark for 1 hour.

Sorry, but this is the most stupid thing I've ever heard.

Under no circumstances an application which uses publicly available programming interfaces should damage your hardware and if it does, then your hardware is 100% faulty (except some very corner cases which are not relevant for this discussion, i.e. you can easily kill your HDD by making it start-stop every second for prolonged periods of time).

Any graphics card should sustain running Furmark during entire its lifetime in 7x24 mode, i.e. if you have a three years warranty for your GTX480, that means it's safe to assume that this GPU must tolerate running Furmark for three years in a non-stop mode.